Abstract
1. Artificial populations containing reciprocal arrangements, A and B, of the third chromosome due to a terminal inversion, In3L, of Drosophila ananassae were studied. All populations reached equilibria at about 60% A and 40% B after 3-4 months.
2. Heterosis regarding the karyotypes, AA, BB and AB, was expressed in longevity, viability, hatchability, fecundity and rate of development.
3. AA was always superior to BB in longevity, viability and rate of development.
4. Some differences between AB and BA heterozygotes raised by reciprocal crosses were observed in fecundity, longevity and rate of development in poor medium with only 5% boiled yeast.
5. Comparing net adaptive values estimated by measuring life cycle components with those from population cage experiments, a close coincidence was ascertained for AB as well as for AA, although an underestimation was found for BB homozygote.
